Structure Analysis And Monitoring Of Cons-Truction Process Of Open Spandrel Trapezoid Box-girder Continuous Rigid Frame Bridge

Open spandrel trapezoid box-girder continuous rigid frame bridge is novel, having the characteristics of the mechanical properties of arch bridge and continuous rigid frame bridge. Based on the FuJiang bridge, the finite element model of open spandrel trapezoid box-girder continuous rigid frame bridge was established.The structure internal force, stress, stability problem in all stages of construction were analyzed in the model, and the key monitoring points were determined, the construction was guided through the monitoring and hthe theoretical value. The conclusions are as follow:(1) Describes the calculation methods to simulate prestressed concrete continuous rigid frame bridge in its stage, which is the forward-calculation method and reversal installation method method.Through the analysis and comparison, to determine the simulation of the open spandrel trapezoid box-girder continuous rigid frame bridge adopt theforward-calculation method,which can significantly reduce the amount of calculation.(2) Based on construction phase partitioning scheme of FuJiang bridge, combined with the forward-calculation method, the whole bridge finite element model is established.The static internal force and the the most unfavorabl normal stress of each unit in every construction stage was analyzed. The results show that the distribution of static internal force is reasonable, in line with the distribution characteristic of the internal force.Throughout the construction process, the the most unfavorable normal stress of each unit are within the specification limits,and the structure strength is guaranteed.(3) Analysising the structure stability of the main girder in the maximum cantilever state and completion stage.The results show that the elastic buckling safety coefficient in completion construction is81.4, the buckling mode of main girderw is vertical bending; In the maximum cantilever state,the elastic buckling safety coefficient is67.6, and the buckling modal was lateral bending of pier.(4) The stress monitoring was conducted in the process of the construction of each construction stage.Analysing the stress of the three main control section.the results show that the stress tendency of the measured values and the calculation values coincide better. Only a few points displayed larger volatility due to those factors,such as concrete creep and shrinkage, ages and temperature, but the stress distribution is accords with the application of load on the whole. (5) Through measuring the elevation, the camber in completion stageand have good alignment with the design camber.the tolerance of most points are within20mm.